Romman for me, huge white clouds. Fumari is decent too...Not as big size wise but it's still dense and white.
I never had huge clouds with AF on the other hand. Though I think what kind of coals and how much you have of it has 80% to do with how big you clouds all. Brand doesn't factor much. That being said, that's probably why Romman gives me the biggest clouds, it's the brand that needs the most coals to get going. Other people can confirm Romman requires more coals, and more coals mean more clouds....